Nuclear cameras, also known as scintillation cameras and gamma cameras are well known medical diagnostic imaging machines which are able to produce images of the gamma radiation field immediate from a medical patient having ingested a small quantity of a radioactive isotope. The large camera head is bulky and heavy, and in order to image better the radiation field, a collimator, usually made of lead, is attached to the aperture of the camera in order to accept gamma radiation within a specified angle of divergence from the line of sight of the camera. These collimators may have a mass ranging between 20 to 100 kg and have a thickness ranging from roughly 5 to 15 cm.
In the case that the camera is mounted to a drum or other form of rotating main frame unit, it is desirable to be able to adjust a radial position of the camera face with respect to its axis of rotatable mounting. Such rotatable mountings are used where the camera is to carry out a computed axial tomography (CAT) scan. Adjusting the radius of rotation of the camera about the patient allows for an adjustment of how close or far from the body axis of the patient the camera is to take its images. As patients may vary in size from children to very large adults, it is an advantage to be able to set the radius of rotation before carrying out a CAT scan.
It is known in the art to make the camera mounting radially adjustable as is shown in Japanese patent publication No. 58-30685 published Feb. 23, 1983. The disadvantages associated with the known mechanical positioner with adjustable radial position is that a separate linear track positioning means must be provided in the portion of the mounting unit which is rotatable about an axis of the patient's body.